Mercedes: Rosberg problem identified, hopeful on Hamilton engine reliability

Mercedes say that they have identified the problem with Nico Rosberg's development engine in Monza and that they believe Lewis Hamilton's similar unit will be okay for the Italian Grand Prix.

Rosberg had to make an urgent change for qualifying back to the old specification unit used in five Grands Prix including Spa, which meant that he did not have all the latest updates and modes and the old engine was not optimised for the new Petronas fuel, introduced here for the new engine. The new unit used up all of Mercedes' seven development tokens, with a raft of upgrades some aimed at performance this season and others with innovations with a view to 2016.

The problem on Rosberg's engine was traced to a leak which meant contamination of water in the oil system. The unit is heading back to Mercedes' Brixworth engine base where it will be comprehensively checked and tested.

It is not known yet whether this engine can continue in the race pool of engines for the rest of this season or whether it will be a write off or indeed whether it may be used simply for practice sessions as a cautionary move.

As for Hamilton's chances in the race today, Mercedes say that they have checked and see no reason for concern.

Ferrari has made clear progress with its car and engine. Its power output has clearly increased with more aggressive qualifying modes, which allowed it to get closer than expected to Hamilton in qualifying.

But less noticeable is that the cornering speeds were very impressive. Ferrari has a new rear wing here to get the right balance between low downforce for the straights and some downforce for the slow corners, but also it has reverted to a bodywork package used before Spain which is very effective on high speed.